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Date:   Fri, 13 May 2022 15:08:18 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Chee Hou Ong <chee.houx.ong@...el.com>,
        Aman Kumar <aman.kumar@...el.com>,
        Pallavi Kumari <kumari.pallavi@...el.com>,
        stable@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net 1/2] Revert "can: m_can: pci: use custom bit timings for Elkhart Lake"

From: Jarkko Nikula <jarkko.nikula@...ux.intel.com>

This reverts commit 0e8ffdf3b86dfd44b651f91b12fcae76c25c453b.

Commit 0e8ffdf3b86d ("can: m_can: pci: use custom bit timings for
Elkhart Lake") broke the test case using bitrate switching.

| ip link set can0 up type can bitrate 500000 dbitrate 4000000 fd on
| ip link set can1 up type can bitrate 500000 dbitrate 4000000 fd on
| candump can0 &
| cangen can1 -I 0x800 -L 64 -e -fb \
|     -D 11223344deadbeef55667788feedf00daabbccdd44332211 -n 1 -v -v

Above commit does everything correctly according to the datasheet.
However datasheet wasn't correct.

I got confirmation from hardware engineers that the actual CAN
hardware on Intel Elkhart Lake is based on M_CAN version v3.2.0.
Datasheet was mirroring values from an another specification which was
based on earlier M_CAN version leading to wrong bit timings.

Therefore revert the commit and switch back to common bit timings.

Fixes: 0e8ffdf3b86d ("can: m_can: pci: use custom bit timings for Elkhart Lake")
Link: https://lore.kernel.org/all/20220512124144.536850-1-jarkko.nikula@linux.intel.com
Signed-off-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Reported-by: Chee Hou Ong <chee.houx.ong@...el.com>
Reported-by: Aman Kumar <aman.kumar@...el.com>
Reported-by: Pallavi Kumari <kumari.pallavi@...el.com>
Cc: <stable@...r.kernel.org> # v5.16+
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/m_can/m_can_pci.c | 48 +++----------------------------
 1 file changed, 4 insertions(+), 44 deletions(-)

diff --git a/drivers/net/can/m_can/m_can_pci.c b/drivers/net/can/m_can/m_can_pci.c
index b56a54d6c5a9..8f184a852a0a 100644
--- a/drivers/net/can/m_can/m_can_pci.c
+++ b/drivers/net/can/m_can/m_can_pci.c
@@ -18,14 +18,9 @@
 
 #define M_CAN_PCI_MMIO_BAR		0
 
+#define M_CAN_CLOCK_FREQ_EHL		200000000
 #define CTL_CSR_INT_CTL_OFFSET		0x508
 
-struct m_can_pci_config {
-	const struct can_bittiming_const *bit_timing;
-	const struct can_bittiming_const *data_timing;
-	unsigned int clock_freq;
-};
-
 struct m_can_pci_priv {
 	struct m_can_classdev cdev;
 
@@ -89,40 +84,9 @@ static struct m_can_ops m_can_pci_ops = {
 	.read_fifo = iomap_read_fifo,
 };
 
-static const struct can_bittiming_const m_can_bittiming_const_ehl = {
-	.name = KBUILD_MODNAME,
-	.tseg1_min = 2,		/* Time segment 1 = prop_seg + phase_seg1 */
-	.tseg1_max = 64,
-	.tseg2_min = 1,		/* Time segment 2 = phase_seg2 */
-	.tseg2_max = 128,
-	.sjw_max = 128,
-	.brp_min = 1,
-	.brp_max = 512,
-	.brp_inc = 1,
-};
-
-static const struct can_bittiming_const m_can_data_bittiming_const_ehl = {
-	.name = KBUILD_MODNAME,
-	.tseg1_min = 2,		/* Time segment 1 = prop_seg + phase_seg1 */
-	.tseg1_max = 16,
-	.tseg2_min = 1,		/* Time segment 2 = phase_seg2 */
-	.tseg2_max = 8,
-	.sjw_max = 4,
-	.brp_min = 1,
-	.brp_max = 32,
-	.brp_inc = 1,
-};
-
-static const struct m_can_pci_config m_can_pci_ehl = {
-	.bit_timing = &m_can_bittiming_const_ehl,
-	.data_timing = &m_can_data_bittiming_const_ehl,
-	.clock_freq = 200000000,
-};
-
 static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
 {
 	struct device *dev = &pci->dev;
-	const struct m_can_pci_config *cfg;
 	struct m_can_classdev *mcan_class;
 	struct m_can_pci_priv *priv;
 	void __iomem *base;
@@ -150,8 +114,6 @@ static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
 	if (!mcan_class)
 		return -ENOMEM;
 
-	cfg = (const struct m_can_pci_config *)id->driver_data;
-
 	priv = cdev_to_priv(mcan_class);
 
 	priv->base = base;
@@ -163,9 +125,7 @@ static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
 	mcan_class->dev = &pci->dev;
 	mcan_class->net->irq = pci_irq_vector(pci, 0);
 	mcan_class->pm_clock_support = 1;
-	mcan_class->bit_timing = cfg->bit_timing;
-	mcan_class->data_timing = cfg->data_timing;
-	mcan_class->can.clock.freq = cfg->clock_freq;
+	mcan_class->can.clock.freq = id->driver_data;
 	mcan_class->ops = &m_can_pci_ops;
 
 	pci_set_drvdata(pci, mcan_class);
@@ -218,8 +178,8 @@ static SIMPLE_DEV_PM_OPS(m_can_pci_pm_ops,
 			 m_can_pci_suspend, m_can_pci_resume);
 
 static const struct pci_device_id m_can_pci_id_table[] = {
-	{ PCI_VDEVICE(INTEL, 0x4bc1), (kernel_ulong_t)&m_can_pci_ehl, },
-	{ PCI_VDEVICE(INTEL, 0x4bc2), (kernel_ulong_t)&m_can_pci_ehl, },
+	{ PCI_VDEVICE(INTEL, 0x4bc1), M_CAN_CLOCK_FREQ_EHL, },
+	{ PCI_VDEVICE(INTEL, 0x4bc2), M_CAN_CLOCK_FREQ_EHL, },
 	{  }	/* Terminating Entry */
 };
 MODULE_DEVICE_TABLE(pci, m_can_pci_id_table);

base-commit: f3f19f939c11925dadd3f4776f99f8c278a7017b
-- 
2.35.1


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